First-principles study of two-dimensional van der Waals heterostructure based on ZnO and Mg(OH)2: A potential photocatalyst for water splitting

Abstract

In this study, the structural, electronic and optical properties of the two-dimensional heterostructure based on ZnO and Mg(OH)2 are investigated by first-principle calculations. The ZnO/Mg(OH)2 heterostructure, formed by van der Waals (vdW) interaction, possesses a type-II band structure, which can separate the photogenerated electron–holes constantly. The heterostructure has decent band edge positions for the redox reaction to decompose the water at pH 0 and 7. As for the interfacial properties of the heterostructure, the trend of band bending of the ZnO and Mg(OH)2 layers in the heterostructure is addressed, which will result a built-in electric field. Besides, the charge-density difference and potential drop across the interface of the ZnO/Mg(OH)2 vdW heterostructure are also calculated. Finally, the heterostructure is demonstrated that it not only has excellent ability to capture the light near the visible spectrum region, but also can improve the optical performance for the monolayered ZnO and Mg(OH)2.